Diabetic retinopathy (DR) and cardiovascular disease (CVD) are common complications of diabetes mellitus, contributing to the high morbidity and mortality in all persons with diabetes, but especially in African-Americans, in whom the prevalence of diabetes is high. Thus, it is of paramount importance to identify early markers for increased risk of these micro- and macrovascular complications, particularly in this high-risk group. In type 1 diabetic white persons, retinal vessel diameter size has been shown to be a predictor of progression of DR and incidence of CVD. Such data need to be repeated and replicated in other populations. The proposed study is designed to examine retinal vessel diameter size-in African-Americans with type 1diabetes-as a potentially useful clinical prognosticator of progression of DR and incidence of CVD (hypertension, coronary disease, stroke, and lower extremity amputation). In order to achieve our goal, we plan to (a) measure diameters of retinal arterioles and venules from baseline digitized retinal photographs of the New Jersey 725, a cohort of type 1 diabetic African-Americans; and (b) analyze these measurements relative to (i) 6-year progression of DR, and (ii) 6-year incidence of CVD. The patient population for our study ("the New Jersey 725") comprises African-Americans with type 1diabetes, who have been diagnosed and treated with insulin before 30 years of age. Of the original cohort of 725 African-American patients, 709 (97.8%) had gradable (i.e., with measurable retinal vessels) baseline retinal photographs. Of these 709, 580 (81.8%) were available for the 6-year follow-up, and of these, 500 (86.2%) had gradable (for retinopathy) retinal photographs. For the present study, each patient's baseline retinal photographs will be digitized, and the diameters of six arterioles and six venules- present within one disc diameter of the optic nerve head-will be measured in one or both eyes. Measurements will be made using a computer imaging program (IVAN), and conducted by four experienced graders at the Ocular Epidemiology Reading Center in Madison, WI, where the retinal photographs are stored. Retinal vessel diameter size will be analyzed relative to 6-year progression of DR and incidence of CVD, adjusting for baseline risk factors for DR and CVD. We have a unique opportunity to examine retinal vessel size (a) as a marker for the severe vascular complications of diabetes and (b) as a clue to the microvascular processes involved in DR and CVD in this high-risk type 1 diabetic African-American population. [unreadable] [unreadable] [unreadable] [unreadable]